79' 360 2BB

F*#KIN lame, & that's all 95% of shops are anymore, nobody "fixes" anything & their lack of knowledge is the primary reason why. Well, seeing Your revision, if this is a
feedback carb, the mixture control solenoid could be bad...hard to come by. That is a very familiar symptom.......................
Pretty sure this could be solved super fast 10 years ago.